Method for rendering a multimedia content and a navigation interface on a screen

ABSTRACT

A method for managing, in a reader terminal, streaming of a televisual content, called the main content, and of a navigation interface concomitantly from a telecommunication network, the navigation interface has regions including contents representative of real-time televisual contents available for selection, which contents are called secondary contents. The method includes the following steps, in the multimedia-stream reader terminal: receiving a command to display the navigation interface; and transmitting a request to access secondary contents of the interface, the request including a datum representative of a type of secondary contents to be streamed, the chosen image type taking into account a datum related to the streaming of the main content.

TECHNICAL FIELD

The field of the invention is that of the transmission of digitalmultimedia contents, namely digital audio and/or video contents. Moreprecisely, the invention relates to the rendition of a content of thenavigation-interface type concomitantly with the rendition of a contentstreamed via a telecommunication network. The invention mostparticularly relates to content streamed using a HAS (HTTP AdaptiveStreaming) technique or any other streaming technique using the sameprinciple.

The invention applies to any device capable of rendering both HAS videocontents and a navigation interface. These devices are for example a TVdongle, a Web TV, a connected television, a digital television decoder,etc.

PRIOR ART

Access to a multimedia content, such as television or video on demand,over the Internet is currently possible for most rendering terminals,especially when they belong to a local communication network, such as ahome network.

The terminal generally sends a request to a server, thereby indicatingthe chosen content, referred to as the main content below; the terminalreceives in return a stream of digital data relating to this content. Inthe context of a local communication network, such a request transitsvia the access gateway of the network, the residential gateway forexample.

The terminal is able to receive these digital contents in the form ofmultimedia data and to carry out a rendition thereof. This renditionconsists in delivering, via the terminal, the digital content in a formthat is accessible to the user. For example, received data correspondingto a video are generally decoded, then rendered via the terminal in theform of a display of the corresponding video with its associatedsoundtrack. Below, for the sake of simplification, the digital contentwill be considered to be a video and the rendition by the terminal, orconsumption by the user of the terminal, will be considered to beviewing of this video on the screen of the terminal.

The transmission of digital contents over the Internet is often based onclient-server protocols of the HTTP family (HTTP being the acronym ofHyperText Transport Protocol). In particular, streaming of digitalcontents allows the data to be transported and consumed in real-time,i.e. the digital data are transmitted over the network and rendered bythe terminal as they arrive. The terminal receives and stores some ofthe digital data in a buffer memory before rendering them. Thisdistribution mode is particularly useful when the bandwidth currentlyavailable to the user is not guaranteed to remain so for the real-timetransfer of the video.

HTTP adaptive streaming (abbreviated HAS) in addition allows data to betransmitted and received with various qualities for examplecorresponding to various bit rates. These various qualities aredescribed in a manifest available to download from a data server, acontent server for example. When the client terminal desires to access acontent, this manifest allows the correct format for the content to beconsumed to be selected depending on the available bandwidth or on thestorage and decoding capacities of the client terminal. This type oftechnique especially allows variations in the bandwidth of the linkbetween the client terminal and the content server to be taken intoaccount.

A number of technical solutions allowing streaming of such a content tobe facilitated already exist, such as for example the proprietarysolutions Microsoft® Smooth Streaming, Apple® HLS, Adobe® HTTP DynamicStreaming or even the MPEG-DASH standard of the organization ISO/IEC,which will be described below. These methods propose to address, to theclient, one or more manifests containing the addresses of the varioussegments with the various qualities of the multimedia content.

Thus, the MPEG-DASH standard (DASH standing for “Dynamic AdaptiveStreaming over HTTP”) is a standard format for audiovisual transmissionover the Internet. It is based on preparation of the content intovarious versions of variable bit rate and quality, said versions beingdivided into segments of short duration (of about a few seconds), whichare also called chunks. Each of these segments is made availableindividually by means of an exchange protocol. The protocol mainlytargeted is the HTTP protocol, but other protocols (FTP for example) mayalso be used. The organization of the segments and the associatedparameters are published in a manifest in XML format.

The principle underlying this standard is that the MPEG-DASH clientterminal estimates the bandwidth available to receive segments, and,depending on how full its reception buffer is, chooses, for the nextsegment to be streamed, a version the bit rate of which ensures the bestpossible quality, and allows a reception delay compatible with anuninterrupted rendition of the content.

Thus, to adapt to variation in network conditions, especially in termsof bandwidth, existing adaptive-streaming solutions allow the clientterminal to pass from a version of the content encoded with a certainencoding bit rate, to another encoded at another bit rate, during thestreaming. Specifically, each version of the content is divided intosegments of same duration. To allow a continuous rendition of thecontent on the terminal, each segment must reach the terminal before itsscheduled rendering time. The perceived quality associated with asegment increases with the size of the segment, expressed in bits, butat the same time, larger segments require a longer transmission time,and therefore have a higher risk of not being received in time for thecontent to be rendered without interruption.

The rendering terminal must therefore find a compromise between theoverall quality of the content and the need to render it withoutinterruption, by selecting the next segment to be streamed with care,from the various proposed encoding bit rates. Algorithms for selectingthe quality of the content depending on the available bandwidth, andwhich may employ strategies of greater or lesser aggressiveness orgreater or lesser security, exist to this end.

The consumption of digital contents via HTTP adaptive streaming (HAS) istending to become more common. HAS is especially used by many streamingservices, but also by certain TV decoders, or set-top boxes, which useit to access delinearized contents such as video on demand (VOD), toreplay television programs, or even to provide services such as NetworkPVR (Network Personal Video Recorder, i.e. a service for recordingdigital contents, the recording being made by the content provideritself rather than in the home of the end-user).

Furthermore, other devices, such as real-time multimedia-stream readerapparatuses, generally access digital contents such as real-time (orlive) televisual contents in an adaptive-streaming mode. This is forexample the case of the apparatus CléTV® supplied by Orange®.

Such an apparatus is conventionally plugged into the HDMI port of atelevision set and communicates, via a Wi-Fi® connection, with anotherapparatus of the home communication network (residential gateway,computer, smart phone, tablet, etc.) that is connected to a wide-areacommunication network such as the Internet, with a view to rendering, onthe television set, the multimedia content received by a compatiblesoftware application. Below, such apparatuses will be referred to asHDMI keys.

The quality of the video delivered to the client terminal will thereforecontinuously adapt to constraints on its access bandwidth, creatingcompetition with all the other services that consume bandwidth and inparticular navigation interfaces. A navigation interface showcasesselectable contents, and allows various live television channels to beaccessed via a list of contents that is called a VZL (Virtual ZappingList). The navigation interface in question may be displayedconcomitantly with a multimedia content, called the main content, beingbroadcast and streamed in HAS mode.

The contents available for selection from the VZL are often associatedwith a multimedia content, called the secondary content. A secondarycontent is often an image but may very well be a video. The display ofthe interface requires images representative of televisual contentsavailable for selection to be retrieved from servers. In addition, theseimages are regularly retrieved because they change depending on the livetelevisual contents that are being broadcast. To provide an optimalquality of service, these images must have a sufficiently high quality,so as to make the interface displayed on the screen pleasant for a userto look at. However, to stream these images and to update them asrequired consumes a lot of bandwidth and sometimes requires the clientterminal to decrease the bit rate of the segments requested for the maincontent being rendered. A decrease in the quality with which the maincontent is rendered results from the various concomitant downloads.

SUMMARY

An exemplary embodiment of invention aims to improve the situation.

An exemplary embodiment of the invention relates to a method formanaging, in a reader terminal, streaming of a televisual content,called the main content, and of a navigation interface concomitantlyfrom a telecommunication network, the navigation interface comprisingregions including contents representative of real-time televisualcontents available for selection, which contents are called secondarycontents, characterized in that it comprises the following steps, in themultimedia-stream reader terminal:

-   -   a step of receiving a command to display the navigation        interface,    -   a step of transmitting a request to access secondary contents of        the interface, the request including a datum representative of a        type of secondary contents to be streamed, the chosen type        taking into account a datum related to the streaming of the main        content.

According to an exemplary embodiment of the invention, simultaneousaccess to two types of contents, namely a televised content and anavigation interface that contains contents, is managed by judiciouslymaking the encoding bit rates of the two types of content vary dependingon the quality desired for each of the contents or even for the setincluding the main content and the navigation interface. It may forexample be desired to prioritize the televised content over thenavigation interface or vice versa.

To achieve this objective, the function of the image-streaming module isto require requests to access the secondary contents to specify aparticular value representative of an image quality, this value beingchosen so as to ensure the navigation interface and/or the televisedstream is rendered with the desired quality.

It will be seen below that the desired quality is dependent on theparticular case; the quality with which the streamed content is renderedmay be given priority over that of the images rendered in the navigationinterface; or vice versa. If the quality desired for the rendition ofthe streamed content is an optimal quality, decreasing the quality ofthe images allows the bandwidth allocated to the main content beingstreamed to be increased and therefore the quality with which the maincontent is rendered to be improved.

According to a first particular embodiment of the invention, the maincontent is streamed in the form of chunks having time-variable encodingbit rates. In this configuration, the datum related to the streaming ofthe main content is a value of the encoding bit rate used for thestreaming. This first embodiment uses an encoding-bit-rate valueavailable to the rendering terminal and therefore has the advantage ofnot requiring any particular computation.

According to yet a second particular embodiment of the invention, whichwill possibly be employed as an alternative or in addition to thepreceding embodiment, the datum furthermore comprises anencoding-bit-rate threshold value not to be crossed when streaming themain content. This embodiment ensures the main content is rendered witha quality at least equal to the predefined encoding-bit-rate threshold.

According to yet a third particular embodiment of the invention, whichwill possibly be implemented alternatively or in addition to thepreceding ones, the datum related to the streaming of the main contentis a value representative of the type of communication network used tostream the main content. In this third mode, the type of image willdepend on the transmission medium of the network; for example, whetherthe network is a fiber network, an ADSL network, etc.

It will be seen that the streaming of the main content and of thesecondary contents are managed by respective streaming modules.According yet a fourth particular embodiment of the invention, whichwill possibly be implemented alternatively or in addition to theprevious ones, the type of image to be used corresponds to an encodingbit rate. This fourth embodiment applies to streaming of images usingHAS. The streaming modules may therefore be combined; in other words,the streaming modules are one module.

According to yet a fifth particular embodiment of the invention, whichwill possibly be implemented alternatively or in addition to thepreceding ones, the datum related to the streaming of the main contentis an encoding bit rate of a value chosen in such a way that the sum ofthe encoding bit rate requested for the secondary contents and thecurrent encoding bit rate used for the main content is lower than agiven maximum encoding-bit-rate value. This fifth embodiment ensuresthat the service encompassing the rendition of a main content and therendition of a navigation interface does not exceed a given encoding bitrate in order to offer an acceptable bandwidth to the other servicesbeing executed by the reader terminal or capable of being executed.

According to a hardware aspect, an exemplary embodiment of the inventionrelates to an entity for managing, in a reader terminal, streaming of atelevisual content, called the main content, and of a navigationinterface concomitantly from a telecommunication network, the navigationinterface comprising regions including contents representative ofreal-time televisual contents available for selection, which contentsare called secondary contents, the televisual content being streamed inthe form of chunks having time-variable encoding bit rates,characterized in that it comprises:

-   -   a module for receiving a command to display the navigation        interface,    -   a module for transmitting a request to access secondary contents        of the interface, the request including a datum representative        of a type of image to be used for the transmission of the        secondary contents, the chosen type taking into account a datum        related to the streaming of the main content.

According to another hardware aspect, an exemplary embodiment of theinvention relates to a reader terminal comprising a managing entity suchas defined above.

According to another hardware aspect, the subject of an exemplaryembodiment of the invention is a computer program able to be implementedon a managing entity such as defined above, the program comprising codeinstructions that, when it is executed by a processor, performs thesteps of the method that are defined above.

According to another hardware aspect, the subject of an exemplaryembodiment of the invention is a data medium on which has been stored atleast one sequence of program-code instructions for executing a managingmethod such as defined above.

The medium in question may be any entity or device capable of storingthe program. For example, the medium may comprise a storage means, suchas a ROM, a CD-ROM or a microelectronic-circuit ROM for example, or elsea magnetic storage means, a hard disk for example. Moreover, the datamedium may be a transmissible medium such as an electrical or opticalsignal, which may be routed via an electrical or optical cable, by radioor by other means. The program according to an exemplary embodiment ofthe invention may in particular be downloaded from an Internet-typenetwork. Alternatively, the data medium may be an integrated circuitinto which the program is incorporated, the circuit being suitable forexecuting or for being used in the execution of the method in question.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiment of the invention will be better understood onreading the following description, which is given by way of example andwith reference to the appended drawings, in which:

FIG. 1 shows an architecture for streaming over the Internet based onthe use of HAS according to an exemplary embodiment of the invention;

FIG. 2 schematically illustrates the hardware structure of a real-timemultimedia-stream reader incorporating a device for managing HASaccording to one embodiment of the invention;

FIG. 3 shows the main elements of the system and a schematic view of thevarious segments of a main content;

FIG. 4 shows an example of rendition of a televised contentconcomitantly with a navigation interface;

FIG. 5 shows the variation in the encoding bit rate used for the maincontent according to the prior art;

FIG. 6 shows the variation in the encoding bit rate used for the maincontent according to one embodiment of the method of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

With reference to FIG. 1, a streaming architecture based on the use ofHAS according to one embodiment of the invention will now be described.It will be noted here, as it was noted above, that the invention is notlimited to the HAS technology but extends to any other technology forstreaming data.

The terminal MOB, which is for example a smart phone, the terminal PC,which is for example a laptop computer, and the terminal CLTV, which isfor example an HDMI key connected to a television set TV, are in thisexample located in a local area network LAN controlled by a residentialgateway GTW. The context of the local network is given by way of exampleand could easily be transposed to a best-effort Internet network, to acorporate network, etc.

A digital-content server SRV is located, in this example, in the widearea network WAN but it could equally well be located in the local areanetwork LAN, for example in the residential gateway GTW or any otherequipment capable of hosting such a content server. The content serverSRV for example receives channels of digital-television content from atelevision broadcaster (not shown) and/or videos on demand, and makesthem available to the client terminals.

The client terminals MOB, PC, CLTV may communicate with the contentserver SRV with a view to receiving one or more contents (films,documentaries, advertisements, etc.).

In this client-server context, to exchange data between the clientterminals MOB, PC, CLTV and the server SRV, an adaptive streamingtechnique based on the HTTP protocol (HAS) is frequently used. This typeof technique especially allows the user to be offered a good contentquality while taking into account variations in bandwidth that may occuron the link between the client terminal MOB, PC, CLTV and the servicegateway GTW, and/or between the latter and the content server SRV.

Conventionally, as will be described with reference to FIG. 3, a givencontent of a channel may be encoded with various qualities, for examplecorresponding to various bit rates. More generally, the term “quality”will be used to refer to a certain resolution of the digital content(spatial resolution, temporal resolution, quality level associated withthe video and/audio compression) with a certain encoding bit rate. Eachquality level is itself divided, in the content server, into temporalsegments (or “chunks”, these two words being used interchangeablythroughout this document).

The description of these various qualities and of the associatedtemporal segmentation, and the chunks, are described for the clientterminal and made available thereto via their Internet addresses (URI:Universal Resource Identifier). All of these parameters (qualities,addresses of the chunks, etc.) are in general grouped together in aparameter file called the manifest. It will be noted that this manifestmay be a computer file or a set of pieces of information describing thecontent, accessible at a certain address.

The terminals MOB, PC and CLTV possess their own characteristics interms of decoding capacity, display capacity, etc. In a HAS context,they may adapt their requests to receive and decode the contentrequested by the user to the quality that best corresponds thereto. Inour example, if the contents are available at bit rates of 512 kb/s(kilobits per second) (resolution 1, or level 1, denoted N1), 1024 kb/s(N2) and 2048 kb/s (N3) and the client terminal has available abandwidth of 3000 kb/s, it may request the content at any bit rate lowerthan this limit, 2048 kb/s for example. Generally, content number i withquality j is denoted “Ci@Nj” (for example the j-th quality level Njdescribed in the manifest).

The service gateway GTW is, in this example, a residential gateway thatroutes the data between the wide area network WAN and the local areanetwork LAN and manages the digital contents; to do this, it especiallyreceives them from the network and decodes them by virtue of decodersthat are here assumed to be integrated into the gateway GTW or into theclient terminals MOB, PC or CLTV. As a variant, the decoders may belocated elsewhere in the wide area network WAN or local area networkLAN, and especially in an STB (acronym of set-top box) (not shown)associated with a television set.

In this example, to display a content, the terminal MOB, PC or CLTVfirstly interrogates the service gateway GTW with a view to obtaining anaddress of the manifest MNF of the desired content (for example, C1).The service gateway GTW responds by delivering, to the terminal, theaddress of the manifest MNF. Below, this file will be assumed to be amanifest according to the MPEG-DASH standard (which file is denoted“C.mpd”).

Alternatively, this file may be retrieved directly from a local Internetserver or an Internet server external to the local network, or alreadybe found in the service Gateway or in the terminal at the moment of therequest.

An example of a manifest (MPD) according to the MPEG-DASH standard andcontaining the description of contents available in three differentqualities (N1=512 kb/s, N2=1024 kb/s, N3=2048 kb/s) of the segmentedcontents is presented in Appendix 1. This simplified manifest describesthe digital contents in an XML syntax (XML being the acronym of eXtendedMarkup Language) and comprises a list of content chunks conventionallydescribed between a start marker (<SegmentList>) and an end marker(</SegmentList>). The division into chunks especially allowsfluctuations in bandwidth to be adapted to, finely. Each chunkcorresponds to a certain duration (field “duration”) with a plurality ofquality levels and allows their addresses (URL—Uniform Resource Locator)to be generated. This generation is done in this example using “BaseURL”elements (“HTTP://servercom”) that indicate the address of the contentserver and “SegmentURL” elements that list the complementary portions ofthe addresses of the various chunks:

-   -   “C1_512kb_1.mp4” for the first chunk of the content “C1” at 512        kilobits per second (“kb”) in the format MPEG-4 (“mp4”),    -   “C1_512kb_2.mp4” for the second chunk,    -   etc.

Once it has the addresses of the chunks corresponding to the desiredcontent, the service gateway GTW obtains the chunks by download fromthese addresses. It will be noted that this download is here achieved,conventionally, via an HTTP URL, but could also be achieved via auniversal resource indicator (URI) describing another protocol(dvb://mysegmentofcontent for example).

A single client terminal, for example the key CLTV that is connected tothe television set TV by being plugged into the HDMI port of the latter,will now be considered. The principle of an exemplary embodiment of theinvention could of course be implemented on the terminals PC or MOB.

The key CLTV is used to render, on the screen of the television set TV,a television program. Below, this television program is referred to asthe content C1. Such a content C1 is described in a manifest MNF.

As a variant, it will be noted that the content C1 may be adelayed-broadcast television program, or a video on demand, or apersonal video of the user, or any other multimedia content of setduration, to which one or more embodiments of the invention alsoapplies.

The key CLTV may be controlled by the user by means of the smart phoneMOB, on which is installed a software application for remotelycontrolling the key CLTV.

The content chunks obtained via the residential gateway GTW are forexample transmitted by WiFi® to the key CLTV, which controls theirdisplay on the screen of the television set TV, with a view to renderingthem to the user.

FIG. 2 shows an architecture of a key CLTV according to one embodimentof the invention.

The key CLTV comprises, as is conventional, memories M associated with aprocessor CPU. The memories may be ROMs (ROM being the acronym of ReadOnly Memory) or RAMs (RAM being the acronym of Random Access Memory) orindeed flash memories. The key CLTV communicates with the local areanetwork LAN and the wide area network WAN via the Wi-Fi module toachieve local wireless communication with the residential gateway GTW oranother communication terminal of the local area network LAN, the smartphone 3 for example. The key CLTV furthermore comprises a streamingmodule HAS suitable for requesting one of the contents to be streamed atone of the qualities proposed in a manifest MNF. This manifest MNF mayfor example be stored in the memories M of the key CLTV or be storedelsewhere.

The key CLTV is connected to a television set TV, via an HDMI link.

The key CLTV furthermore comprises a module IMG for streaming secondarycontents, which module is described below, and a streaming module HASfor managing the streaming of contents in HAS mode.

The key CLTV may also contain other modules such as a hard disk (notshown) for storing video chunks, a module for controlling access to thecontents, and a module for processing commands received from the smartphone.

Now, with reference to FIG. 3, the main elements of a key CLTV and aschematic view of a main content C1 stored in the content server SRV inthe form of segments will now be described. More precisely, the contentserver HAS contains a video C1 that is divided into chunks C1i@Nj thatare encoded at various encoding bit rates N, where the index i is atemporal identifier of the chunk C1i@Nj.

In the prior art, the streaming module HAS of the key CLTV isresponsible for retrieving these chunks from the content server HAS andchooses the video quality Nj depending on the available networkresource. The way in which the streaming module HAS chooses the encodingbit rate of the next video chunk to be streamed will not be described indetail here: specifically, there are many algorithms allowing thischoice to be made, the security and aggressiveness of the strategies ofwhich vary. It will however be recalled that, most often, the generalprinciple of such algorithms is based on the download of a first chunkat the lowest encoding bit rate proposed in the manifest, and on theevaluation of the time taken to retrieve this first chunk. On thisbasis, the streaming module HAS evaluates whether, depending on the sizeof the chunk and on the time taken to retrieve it, the networkconditions allow the following chunk to be streamed at a higher encodingbit rate. Certain algorithms are based on a gradual increase in thequality level of the streamed content chunks; others propose more riskyapproaches, with jumps in the levels of the encoding bit rates ofsuccessive chunks.

In the conventional case, if a video chunk last 3 seconds, the retrievalof the chunk by the streaming module HAS must not take more than 3seconds, in order to allow the content to be rendered by the key CLTVwithout interruption. It is therefore necessary for the streaming moduleHAS to find the best compromise between the rendition quality, andtherefore encoding bit rate, which must be as high as possible, and thetime taken to stream the chunk, which must be low enough to allow acontinuous rendition on the television set TV.

In the embodiment illustrated in FIG. 3, the streaming module HAScommands the download of a chunk at the optimal encoding bit rate asdescribed in detail below.

Initially, the module HAS retrieves the manifest MNF that corresponds tothe video content C1 in order to discover the available chunks of thevideo content C1, and the various associated video qualities Nj. In theexample of FIG. 3, the content C1 is for example available in the formof chunks of 3 s duration, with a first encoding bit rate N1=500 kb/s, asecond encoding bit rate N2=2000 kb/s, a third encoding bit rate N3=2000kb/s, etc.

In a normal operating mode (not illustrated in FIG. 3), the module HASfor example streams the successive chunks C11@N1 (i.e. the firsttemporal chunk at an encoding bit rate of 500 kb/s), then C12@N3 (i.e.the second temporal chunk at an encoding bit rate of 2000 kb/s), thenC13@N3 (i.e. the third temporal chunk at an encoding bit rate of 2000kb/s), etc.

The various chunks streamed by the streaming module HAS are transmittedto an interface module INT with a view to rendition thereof to the useron the screen of the television set TV. The module INT manages theinterface with the television set TV, via which it for example obtainsinformation on any interactions of the user with the television set TV(action on the remote control of the television set, for example a presson the volume button or a button for changing channel), and via which itmay control the display on the screen of the television set TV of arequested content, for example a television channel and a navigationinterface concomitantly.

The algorithm employed by the streaming module HAS to determine whichchunk at which encoding bit rate must be streamed in normal operatingmode may be one of the algorithms already known in the prior art. Thisalgorithm will therefore not be described in more detail here.

As indicated above, a navigation interface is accessible and may berendered at the same time as the video content C1 on the screen. Thenavigation interface INT comprises secondary contents that are able tobe streamed with a view to respective renditions thereof on the screen.

Contents other than the video content C1, i.e. the main content, and thesecondary contents may be streamed concomitantly. However, to simplifythe description of an exemplary embodiment of the invention, it will beassumed that the only services being used are streaming of the maincontent, by the streaming module HAS, and streaming of the secondarycontents, in our example images, by the image-streaming module IMG.

In our exemplary embodiment, the main content C1 is a televised content.

FIG. 4 illustrates a screen ECR concomitantly displaying a main contentC1 and a navigation interface NAV.

The interface NAV comprises, in our example, four regions associatedwith four secondary contents CS1-CS4 that are available for selection,respectively. In other words, a user may zap the main content C1 to asecondary content by selecting one of the secondary contents, forexample using a remote control.

A secondary content may irrespectively be an image, a succession ofimages, or a video extract from the content.

In our example, the secondary contents CS1-CS4 are images representativeof contents able to be selected and to be rendered by way of maincontent. Most the time, the image is related to the proposed content. Ifa television channel is broadcasting a cartoon, the associated image inthe navigation interface is for example an image of a scene of thecartoon.

In FIG. 4, the displayed content includes a televised content C1 in thebackground and the navigation interface INT in the foreground. Theinterface INT comprises a drop-down menu (not shown) allowing televisionchannels other than those that are displayed to be accessed. ImagesCS1-CS4 are associated with the television channels accessible from theinterface.

FIG. 5 illustrates the variation in the encoding bit rate selected bythe streaming module HAS as a function of time according to the priorart.

In a first phase PH1, the streaming module HAS selects, for the maincontent C1, a first bit rate N1 and receives segments with this encodingbit rate N1.

In a second phase, which starts at a time t1, a user requires thenavigation interface INT to be displayed.

Following the request to access the interface INT, a request to accessthe images CS1-CS4 is transmitted to the server SRV via the network.Because of the decrease in bandwidth related to the reception of theimages of the interface, the streaming module HAS decreases the encodingbit rate to use for the segments to come from the value N11 to the valueN12. The obtained bit rate value N12 is maintained throughout a secondphase PH2, which corresponds to the length of time taken to stream theimages, namely the length of time between the times t1 and t2.

Once the images of the interface have been streamed, the bandwidthincreases and the client HAS re-adapts the encoding bit rate to thesegments to be streamed. The module HAS once again selects the bit rateN12 and maintains it throughout a third phase PH3 that ends at the timet3, which corresponds to a time at which all or some of the images areupdated. In our example, these updates occur periodically.

As with the second phase PH2, a fourth phase PH4 occurs after the thirdphase PH3, in which phase, because of the decrease in the bandwidthrelated to reception of the updates of the images of the interface, thestreaming module HAS makes a decrease of X kb/s. The obtained bit ratevalue N12 is maintained throughout this fourth phase PH4, whichcorresponds to the length of time taken to stream the updates of theimages, namely the length of time between the times t3 and t4.

Nevertheless, a problem arises when a given image quality is desired forthe rendition of the main content C1. In this case, the module HASpreferably must not select an encoding bit rate lower than a thresholdencoding bit rate DES. To solve this problem, according to an exemplaryembodiment of the invention, the request to access the navigationinterface comprises a datum representative of a type of image to bestreamed, the chosen image type taking into account a datum related tothe streaming of the main content. The datum related to the streaming ofthe main content is for example a value of the encoding bit rate usedfor the streaming. The data may also be complemented by a thresholdencoding-bit-rate value DEs not to be crossed when streaming the maincontent C1, to ensure a given image quality. For example, the thresholdencoding bit rate DEs may be set to 1024 kb/s. In this configuration,the streaming module IMG may require a given image quality chosen from aplurality of image qualities to respect the threshold encoding bit rateset by the streaming client HAS. This embodiment of the invention isdescribed with reference to FIG. 6.

FIG. 6 contains the same phases as those described with reference toFIG. 5, the only difference being that the image quality requested bythe image-streaming module IMG varies over time. In our example, theimages requested by the streaming module IMG have a quality lower thanthe preceding example and thus occupy less bandwidth, to the advantageof the televised content C1 which therefore sees a larger bandwidth andmay therefore require an encoding bit rate N22 higher than N21 and aboveall higher than the threshold bit rate DEs. In other words, the bit rateN22 requested by the streaming client HAS has a bit rate intermediatebetween the bit rate N11 and the bit rate DEs.

It will be noted here that the invention is obviously not limited to twoimage qualities but extends to a higher number of image qualities.

According to one variant, the datum related to the streaming of the maincontent is an encoding bit rate of a value chosen in such a way that thesum of the encoding bit rate requested for the secondary contents andthe current encoding bit rate used for the main content is lower than agiven maximum encoding-bit-rate value. This variant is advantageous whenthe rendition of a main content and the navigation interface forms partsof a given service and it is desired not to exceed a given bandwidth andtherefore to be able to provide a comfortable amount of headroom withrespect to access bit-rate to the other services able to be executed atthe same time on the key CLTV.

To illustrate the example described with reference to FIG. 6, let forexample the current bandwidth of access to the network RES be about 8Mb/s and the current encoding bit rate C1i@Nj of the received chunks tobe 5 Mb/s. The image-streaming module IMG therefore in theory has aremaining bandwidth of 3 Mb/s available to it.

Let it also be assumed that the threshold encoding bit rate DEs is setto 4 Mb/s, the image-streaming client IMG will therefore set the imagequality to 2 Mb/s or less and thus allocate 3 Mb/s as remainingbandwidth to the streaming module HAS of the televised content.

Assuming that the two available image qualities are associated with bitsrates of 2 Mb/s and 4 Mb/s, the streaming client will select the bitrate of 2 Mb/s.

As a variant, the data representative of a type of image to be streamedmay also be defined by virtue of parameters such as height, width,compression ratio, etc., the content servers SRV being tasked withdelivering the requested content with the delivered parameters.

According to a last variant, the datum related to the streaming of themain content is a value representative of the type of communicationnetwork used to stream the main content. For example, if the networkused to stream the televised content is a network that has a highperformance in terms of bandwidth, a fiber network for example, thequality chosen for the images will preferably be a good quality. Incontrast, if the network is of lower performance, such as for example anADSL network, the chosen quality will be lower.

1. A method comprising: managing, in a multimedia-stream readerterminal, streaming of a televisual content, called a main content, andof a navigation interface concomitantly from a telecommunicationnetwork, the navigation interface comprising regions including contentsrepresentative of real-time televisual contents available for selection,which are called secondary contents, wherein the managing comprises, inthe multimedia-stream reader terminal: a. receiving a command to displaythe navigation interface; and b. transmitting a request to access thesecondary contents of the interface, the request including a datumrepresentative of a chosen type of the secondary contents to bestreamed, the chosen type taking into account a datum related to thestreaming of the main content.
 2. The method according to claim 1,wherein the main content is streamed in the form of chunks havingtime-variable encoding bit rates, and the datum related to the streamingof the main content is a value of the encoding bit rate used for thestreaming.
 3. The method according to claim 2, wherein the datumfurthermore comprises an encoding-bit-rate threshold value not to becrossed when streaming the main content.
 4. The method according toclaim 1, wherein the datum related to the streaming of the main contentis a value representative of a type of communication network used tostream the main content.
 5. The method according to claim 1, wherein thetype of secondary content to be used corresponds to an encoding bitrate.
 6. The method according to claim 2, wherein the datum related tothe streaming of the main content is an encoding bit rate of a valuechosen in such a way that the sum of the encoding bit rate requested forthe secondary contents and the current encoding bit rate used for themain content is lower than a given maximum encoding-bit-rate value. 7.An entity for managing, in a reader terminal, streaming of a televisualcontent, called a main content, and of a navigation interfaceconcomitantly from a telecommunication network, the navigation interfacecomprising regions including contents representative of real-timetelevisual contents available for selection, which contents are calledsecondary contents, wherein the entity comprises: processor; and anon-transitory computer-readable medium comprising instructions storedthereon which when executed by the processor configure the entity to: a.receive a command to display the navigation interface; and b. transmit arequest to access the secondary contents of the interface, the requestincluding a datum representative of a chosen type of secondary contentsto be streamed, the chosen type taking into account a datum related tothe streaming of the main content.
 8. The entity according to claim 7,wherein the entity is comprised in the reader terminal.
 9. (canceled)10. A non-transitory computer-readable data medium on which at least onesequence of program-code instructions has been stored, which whenexecuted by a processor of a multimedia-stream reader terminal configurethe multimedia-stream reader terminal to manage streaming of atelevisual content, called a main content, and of a navigation interfaceconcomitantly from a telecommunication network, the navigation interfacecomprising regions including contents representative of real-timetelevisual contents available for selection, which are called secondarycontents, the managing comprising: receiving a command to display thenavigation interface; and transmitting a request to access the secondarycontents of the interface, the request including a datum representativeof a chosen type of the secondary contents to be streamed, the chosentype taking into account a datum related to the streaming of the maincontent.